Sometimes, zoos can have too much of a good thing

The San Diego Zoo's female elephants, including these two, are all on contraception. Their advanced age could cause complications during a pregnancy, said zoo spokeswoman Yadira Galindo. / Photo by Peggy Peattie, U-T

The San Diego Zoo's female elephants, including these two, are all on contraception. Their advanced age could cause complications during a pregnancy, said zoo spokeswoman Yadira Galindo. / Photo by Peggy Peattie, U-T

A couple of female Visayan warty pigs dig for food in their enclosure at the San Diego Zoo. They are kept separate from their male counterparts to prevent breeding. / Photo by Peggy Peattie, U-T

At the San Diego Zoo and Safari Park, animal births are normally celebrated. Photographs are snapped. Naming contests are held. Pandas? Oh, the zoo goes ape when it comes to the arrival of a new panda.

In some cases, though, the zoo doesn’t want a bundle of joy.

An animal may be getting up in age and a pregnancy might be dangerous. The males and females could be too closely related, causing concerns about inbreeding. The animals may be just too good at making babies, leading to overpopulation.

So like zoos nationwide, the one here does gender separation or puts the creatures on birth control. Affected species include lions, Visayan warty pigs, sika deer and elephants, among others.

“The zoo’s female elephants are all on contraception,” said Yadira Galindo, a zoo spokeswoman. “The advanced age could cause complications during a pregnancy, so the decision was made to put them on contraception.”

Zoos nationwide do this. It’s a little bit ironic, though. Many zoos work tirelessly to preserve those species that are threatened and endangered in the wild. But the zoos also have to make sure some animals they house don’t strain their facilities’ limited spaces by procreating at a rate that’s unsustainable.

Take the sika deer at the Safari Park, for instance. That species of Asian deer doesn’t have a problem when it comes being fruitful and multiplying. So some of the males have undergone vasectomies. If males are needed again to breed, the vasectomies are reversed.

These are the more drastic measures undertaken to avoid unwanted pregnancies, though. The zoo prefers, when it’s possible, merely to separate the males and females.

That’s the case with Visayan warty pigs. They’re critically endangered and hadn’t been bred in zoos outside of the Philippines, according to the zoo. But they must like the air in San Diego or something. They were so prolific they had to be separated. All the ones on exhibit at the zoo are females.

For some species, that’s perfectly natural. In the wild, many deer species form bachelor herds and stay away from the females until nature calls.

But for others, it’s more complicated. Take the zoo’s lions, Mbari and Etosha. They live together because that’s what lions do in the wild. But Etosha has given birth twice and suffered complications, so the zoo made the decision to sterilize her.

Contraception for zoo animals is not something that’s universally accepted. A number of European zoos don’t believe in the practice, arguing that it’s unfair for animals not to experience the joys of sex, pregnancies and parenthood. In the wild, after all, this is what animals do.

But that philosophy causes its own set of problems. If the offspring is unwanted, it’s sometimes killed. In some cases, the meat is fed to the lions.

“It’s a cultural difference,” said Cheryl Asa, the director of the Association of Zoos and Aquariums’ Wildlife Contraceptive Center at the St. Louis Zoo. “I can’t imagine people in the United States accepting that practice.”